This sauce is surprisingly creamy, even before the optional sour cream is added at the finish. In the original recipe, the seeds are finely ground in a spice grinder; the method here creates a sauce that is not quite as smooth.
Serve with fresh hot tortillas or crusty French bread. Despite the temptation to do so, it is better not to serve it atop rice, or all the lovely sauce will be sopped up and lost for dipping.
Servings: 6 - 8
Yield: Makes 6 main-course servings or 8 first-course servings
- 1 1/2 pounds shell-on medium shrimp (31-35 count)
- 2 1/2 cups cold water
- 1 teaspoon salt, or to taste
- 1 cup raw hulled pumpkin seeds
- 1/2 small white onion, coarsely chopped (about 1/3 cup)
- 1/2 bunch cilantro, washed well and coarsely chopped (stems included)
- 2 small serrano chili peppers, stemmed and cut into 1/2-inch pieces (not seeded)
- 2 tablespoons unsalted butter
- 2/3 cup sour cream (optional)
Peel and devein the shrimp, leaving the tails on; set the shrimp aside. Place the shells in a large saucepan with the water and salt over medium heat. Cook for about 20 minutes to make a light broth.
Strain and reserve the broth; discard the shells.
Allow the broth to cool slightly, then return to the saucepan over low heat. Add the shrimp and cook for about 3 minutes, tossing them occasionally, until they are pink and just barely opaque. Strain, reserving the broth in a medium bowl so that it can cool.
Place the pumpkin seeds in a large, dry skillet over medium heat. Cook for 5 to 8 minutes, stirring frequently, until they begin to swell up and pop about; do not let them brown. Let cool completely, then place one-third of them in a blender with about a third of the cooled broth. Puree until fairly smooth, then add another third of the shrimp broth and another third of the seeds, along with the onion, cilantro (stems and leaves) and chili peppers. Puree until smooth, then add the remaining broth and seeds. Scrape down the sides of the blender and puree until smooth, forming a pale pistachio-green sauce.
Melt the butter in a large, heavy saucepan over low heat. Add the blended sauce and cook for about 5 minutes, stirring and scraping the bottom constantly. (Be careful to keep the heat low; more heat will darken the color and change the flavor of the sauce.) The fats from the seeds will help emulsify and thicken the sauce.
Add the shrimp and stir to coat. Cook for 5 minutes, stirring frequently, to finish cooking the shrimp.
Add the sour cream, if desired, and taste to adjust the seasoning as needed; heat through, stirring frequently. Serve immediately.
Adapted from a recipe of Angel Delgado in Restaurante las Diligencias in Tampico, Mexico, in Diana Kennedy's "The Essential Cuisines of Mexico (Clarkson Potter, 2000).
Tested by Diana Kennedy.
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